Wireless transmitter



Dec. 22,1925 ,657 w. T. DITCHAM v WIRELESS TRANSMITTER Original Filed 18, 1920 nmamtoz .T DITC HAM $31 11; attain e4 Patented Dec. 22, 1925.

UNITED STATES WILLIAM THEODORE DITCI'IAM, OF LEBANON PARK, ENGLAND, ASSIGNOR TO RADIO CORPORATION OF AMERICA, A CORPORATION OF DELAWARE.

WIRELESS TRANSMITTER.

Original application filed December 18, 1920, Serial No. 431,582. Patent No. 1,454,598, dated May 8,

To all to from it may concern Be it known that I, WVILLIAM THEODORE DITCHAM, a subject of Great Britain, residing at Kildary, Lebanon Park, in the county of Middlesex, England, have invented certain new and useful Improvements in lVireless Transmitters, of which the follow ing is a specification accompanied by drawings.

The object of this invention is to'provide an improved valve transmitter in which the transmission of the interfering noises, known as key clicks, may be avoided and the valves may be relieved of the full load during the spacing period of the Morse characters.

This application is a division of my application Serial No. 431,582 filed December 18, 1920 for wireless transmitters now Patent No. 1,454,598, patented May 8, 1923.

The above identified application discloses a system wherein an oscillating valve is arranged to be energized from an alternating current source, the alternating current being rectified before being impressed across the plate and filament of the valve.

The invention claimed in the said application comprises providing in the alternating current supply line an impedance or choke coil of such value that the valve will oscillate at substantially the same frequency regardless of whether the impedance or choke coil is in circuit or short circuited. A key is provided for short-circuiting the said impedance or choke coil. The operation of the invention is as follows:

When the key is open the impedance or choke coil is connected in the alternating current supply line and consequently the tube will oscillate but will not supply sufficient power to transmit to any distance.

However, when the key is closed, shortcircuiting the impedance or choke coil, the valve will oscillate with full power and thereby transmit signals. The modification covered by this application is illustrated in the single figure of the accompanyingdrawing.

It is an object of the invention herein claimed to provide means for operating the tube from a D. C. source, such as a D. C.- generator designated as 9 in the drawing.

Divided and this application filed February 8, 1923.

Serial No. 617,894.

In the supply line from this generator I provide a resistance 7 of such value that when it is in circuit the tube will continue to oscillate feebly but at substantially the described my invention, what I claim is 1. In a wiielesstransmitter the combina tion of an oscillating valve, a circuit conf taining a source of direct current supply for said valve, and signalingmeans for variating the amplitude of the oscillations of said valve while maintaining a frequency constant, said signaling means comprising aresistance interposed between said source of supply and said valve'and aninterrupt-er for short circuiting said resistance.

2. In a wireless'transmitter, the combination of an oscillating valve, a circuit containing a source of direct current supply for said valve, a resistance interposed between said source of supply and said valve, said resistance being of such value that the valve will oscillate at substantially the same frequency regardless of whether said resistance is included in the circuit and means for short-circuiting said resistance.

3. In a wireless transmitter, the combination of an oscillating valve, having a filament, grid and plate electrodes, a circuit connecting the filament and the grid electrode, a second circuit connecting the plate i and filament electrodes coupled to the first circuit, a source of direct current supply in the plate filament circuit of said valve, signaling means for varying the amplitude of the oscillations of said valve while maintaining the frequency constant, said signal- WVILLIAM THEODORE DITCHAM, 

